<!DOCTYPE HTML>
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    <title>navigator</title>
    <script type="text/javascript">
        function validB() {
            var u_agent = navigator.userAgent;
            var B_name = "不是想用的主流浏览器!";
            if (u_agent.indexOf("Firefox") > -1) {
                //Firefox
                B_name = "Firefox";
            } else if (u_agent.indexOf("Chrome") > -1) {
                B_name = "Chrome";
            } else if (u_agent.indexOf("MSIE") > -1 && u_agent.indexOf("Trident") > -1) {
                B_name = "IE(8-10)";
            }
            document.write("浏览器:" + B_name + "<br>");
            document.write("u_agent:" + u_agent + "<br>");
        }
    </script>
</head>
<body>
<form>
    <input type="button" value="查看浏览器" onclick="validB()">
</form>
</body>
</html>